-LRB- CNN -RRB- -- At his heaviest , Brent Schmitt weighed 419 pounds . Even at 6 feet 3 inches tall , that was very overweight and he had high blood pressure .

Many people in his family -- aunts , uncles and grandparents -- suffered from diabetes , high cholesterol , heart disease and high blood pressure .

The iReporter 's life-changing moment came during an intense family discussion back in 2009 about his relatives ' ailments .

It finally clicked for him : It was time for him to take a different path .

`` If I did n't do something about my health , then I was concerned I 'd never live long enough to get married and have children or be healthy enough to spend quality time with my future family , '' the Evansville , Indiana , man said .

And in 15 months , he dropped 177 pounds , more than 40 percent of his body weight .

View Brent Schmitt 's iReport

Starting a family is important to this 27-year-old civil engineer and he did n't want to miss out on this opportunity , or the chance to lead a healthy life .

Schmitt jump-started the first six months of his weight loss journey back in July 2009 by reducing his food portions . He would use a smaller dinner plate than in the past and fill it with what he wanted to eat . Once he had done this , he would take half the food off his plate and just consume that portion .

As part of his diet , Schmitt avoided processed foods .

`` I tried to buy fresh fruit and vegetables every three days , along with lunch meat sliced from the deli section of my local grocery store , '' he noted .

Schmitt focused on moving more , too . During the first six months of his weight loss plan , he made the daily choice of moving his body more than he had in the past . He would do little things like take the stairs rather than the elevator - or head to the copy machine after printing a work document , instead of letting his copies stack up .

Once he hit the six-month mark of his lifestyle change , he added more rigorous activity to his daily routine , like using the treadmill . At first , he just walked on the treadmill , but over time he picked up his pace and started to run .

In October 2010 , he reached a milestone , running the Evansville half-marathon in less than two hours .

`` At first I was in disbelief that I finished , and then I was relieved and proud of myself for achieving a difficult goal , '' he said .

He now makes a point to take the longest route possible when walking somewhere in order to get more exercise .

`` It 's everyday choices like these that help me lose weight , '' he added .

It took Schmitt about six and a half months to lose his first 100 pounds and then he shed the last 77 pounds over the next eight and a half months . He hopes to eventually reach his goal weight of 230 pounds .

Dr. Melina Jampolis , CNNHealth 's Diet and Fitness expert who 's a physician nutrition specialist who practices in Los Angeles and San Francisco , California , said Schmitt has shed his weight in a safe and effective manner and she salutes him for making smart choices .

`` He did n't do any crazy diets or jump into a crazy exercise schedule - and he focused on proper nutrition , '' Jampolis said . `` His story just proves that in real life , if you make small choices like these day after day , it can end with tremendous results . ''

Schmitt 's family doctor , Dr. Michael Allen , said he was comfortable with the pace of the weight loss , since he was a young male and did n't have major health issues , beyond his high blood pressure . Allen noted if Schmitt had n't dropped the pounds , he would have been on his way to bigger health problems , including diabetes or possible knee replacement surgery .

Many people who have not seen Schmitt in a long time often do not recognize him , since his looks have dramatically changed . Many will ask him which diet plan he used or if he had bariatric surgery .

`` I have to constantly reinforce the fact that it was a lifestyle change for me , and not a fad diet or surgery that caused me to lose so much weight , '' he added .

Schmitt credits his family and friends for supporting him through his `` lifestyle change . '' He says on days when he felt like he was struggling , they would remind him of his progress and how proud they were of him .

`` They encouraged me to keep going , '' he said .

Schmitt said his family members , with their various health issues , have closely watched his transformation , and he hopes his new healthy life will inspire them to make their own changes one day .

Schmitt 's goal of starting his own family is on track , too . In mid-June , he became engaged and plans to marry his fiancée in November 2012 .

`` Life is good for me right now and the future is bright , '' said Schmitt . `` I feel healthier , have more energy , more self-confidence and feel as though I have accomplished something really great . ''

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CNN iReporter Brent Schmitt shed 177 pounds in 15 months

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Schmitt lost weight by cutting back on food portions and exercising more

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A physician nutrition specialist says Schmitt lost his weight in a safe manner